1. Field of the Invention
This invention relates to machine tools and, more particularly, to a machine tool assembly that can be operated with the machine tool assembly in different orientations.
2. Background Art
Designers of machine tools attempt to achieve a number of different goals. First of all, accuracy is of utmost importance in the design of any machine tool. At the same time, it is desirable to make machine tools to have a relatively compact construction.
A conventional machine tool construction is shown in FIGS. 1-3 herein at 10. The machine tool 10 consists of a base 12 with an upper surface 14 supporting machine tool components, in this case a workpiece holder 16 and a machining unit 18, for performing a machining operation on a workpiece 20 on the workpiece holder 16.
In designing the base 12 forthe machine tool components 16,18, there are a number of considerations. First of all, the height of the upper surface 14 above the subjacent surface 22, as indicated by the double-headed arrow 24, is generally selected to match the waist height for an operator 28, as indicated by the double-headed arrow 26. Consequently, the base 12, by reason of this height requirement, has a substantial mass. Since the base 12 is commonly constructed from a heat conductive material, the larger the mass, the more heat retention there is during operations and the more the base becomes prone to thermally induced deformation. The potential deflection of spaced ends of the base 12, due to heating, is shown schematically in FIG. 3, as indicated by the dotted lines 12. Any base deformation potentially causes a misalignment of the cooperating workpiece holder 16 and machining unit 18, which may detract from the accuracy of any machining operation.
This conventional type of machine tool 10 is normally constructed by building the components thereof in a pyramidal-type fashion for stability. That is, inherently the overall stability of the machine tool 10 is established and maintained by stacking components, as indicated by the arrows 30, like building blocks of decreasing mass, from bottom to top. This construction is desired for stability in this type of system and is classified as an open loop system.
As seen in FIG. 3, an open loop system is one wherein the operating components and the base are not structurally contiguous. In FIG. 3, it can be seen that the machining unit 18 has a cantilevered working end 32 which operates on the workpiece 20 which is cantilever supported from the workpiece holder 16. Thus, the structural loop, as indicated by the arrows 34, is interrupted between the machining unit 18 and the workpiece holder 16. Consequently, any deformation of the base 12 may cause a relative repositioning of the workpiece holder 16 and machining unit 18 so as to potentially detract from the accuracy of any machining operation. Similarly, any movement of the workpiece holder 16 and machining unit 18 relative to each other and the base 12 may have the same consequences.
In one form, the invention is directed to a machine tool assembly having a frame, a workpiece holder, and at least one machining unit that is operable to perform an operation on a workpiece in an operative position on the workpiece holder. The frame has first and second spaced end supports and at least one reinforcing element which extends between the first and second end supports so as to maintain the first and second end supports in a desired operative relationship. The workpiece holder and at least one machining unit each are connected to at least one of the first and second end supports and at least one reinforcing element so that the machining unit can be operated to perform an operation on a workpiece in an operative position on the workpiece holder.
In one form, the first and second end supports have the form of a disk-shaped element, with the at least one reinforcing element having the shape of a first elongate bar.
The elongate bar may extend through at least one of the first and second end supports.
The frame may further include a second elongate bar, with each of the first and second elongate bars having a length, with the lengths of the first and second elongate bars being substantially parallel.
The frame may further include a third elongate bar.
The frame may further include a third disk-shaped element which is connected to the first elongate bar.
The at least one reinforcing element may be in the form of a first elongate plate.
The frame may include a second elongate plate which connects to the first and second end supports.
The first elongate bar may include first and second joinable parts.
The first and second joinable parts may be extendable, one within the other.
In one form, the first joinable part has an annular inside surface and the second joinable part has an annular outside surface with the at least one reinforcing element including a wedge assembly with a first wedge element between the annular inside surface of the first joinable part and the annular outside surface of the second joinable part.
The wedge assembly may further include a second wedge element between the annular inside surface of the first joinable part and the annular outside surface of the second joinable part.
The first and second wedge elements may act directly against each other.
The second wedge element may be threadably engaged with the second joinable part.
The wedge assembly may further include a wedge repositioning element which can be directed into the first joinable part to reposition at least one of the first and second wedge elements.
In one form, the first joinable part has an end and the wedge repositioning element has a shoulder which is abuttable to the end of the first joinable part to limit movement of the wedge repositioning element into the first joinable part.
The first elongate bar may have a through passageway.
A temperature controlling fluid may be directed through the passageway of the first elongate bar.
In one form, the first elongate bar has a cross-sectional configuration taken transversely to its length which is substantially circular.
This cross-sectional configuration may be non-circular or polygonal.
In one form, the first and second end supports each include a disk-shaped element with a perimeter edge defining substantially a circular shape.
The perimeter edges of the end supports may define a square shape.
In one form, the perimeter edges have spaced projections which may be bridged by a support upon which the machine tool assembly is placed.
The shape of the peripheral edges of the first and second end supports may be substantially the same.
In one form, the first and second end supports and at least one reinforcing element cooperatively define a caged working space within which a machining operation may be performed by the at least one machining unit.
In one form, the first and second end supports have first and second facing surfaces which bound a working space and the at least one machining unit is mounted on the first facing surface.
In one form, the first end support has oppositely facing first and second surfaces on the first and second opposite sides of the first end support and the workpiece holder is on the first side of the first end support and the at least one machining unit is on the second side of the first end support.
The first end support may have an opening through which a workpiece held by the workpiece holder can be directed to be operated upon by the at least one machining unit.
In one form, the frame, workpiece holder, and at least one machining unit define a machine tool module that can be operated in any orientation.
In one form, the frame defines a passageway for guiding movement of a temperature controlling fluid.
In one form, the at least one reinforcing element has a first elongate hollow bar, the frame has a second elongate hollow bar extending between the first and second end supports, and a passageway for temperature controlling fluid is defined through the first and second elongate hollow bars.
The passageway may be continuous to permit circulation of a temperature controlling fluid.
A pump may be provided for circulating temperature controlling fluid in the passageway.
The machine tool assembly may further include a temperature controlling fluid in the passageway.
The invention is also directed to the combination of a base and a first machine tool assembly that can be placed in an operative position on the base in an elevated position over a subjacent support surface, with the machine tool assembly having the configuration as described above.
The combination may further include a second machine tool assembly substantially the same as the first machine tool assembly that can be placed in an operative position on the base and in an elevated position over a subjacent support surface so that machining operations can be performed simultaneously by the first and second machine tool assemblies.
The base may define a reservoir for collection of workpiece particles and machining fluids generated during machining operations.
The base may have stepped surfaces for the first and second machine tool assemblies.
The end supports on the first and second machine tool assemblies may be supported directly against the base.
In one form, the at least one reinforcing element on the first and second machine tool assemblies does not directly engage the base.
The end supports on the first and second machine tool assemblies may each have a perimeter surface that is substantially circular.
Connectors may be provided for joining between the base and at least one of the end supports on each of the first and second machine tool assemblies to maintain the first and second machine tool assemblies in the operative position on the base.
The base may include a frame defining a plurality of compartments each configured to receive a machine tool assembly substantially the same as the first machine tool assembly.
The invention is further directed to a machine tool assembly having a frame, a workpiece holder, and at least one machining unit that is operable to perform an operation on a workpiece in an operative position on the workpiece holder. The frame defines a cage with an external surface which permits different portions of the external surface of the machine tool assembly module to be placed against a support surface to permit performance of a machining operation with the machine tool assembly module in different orientations.
In one form, the frame has a lengthwise axis and the external surface of the frame is configured to extend substantially fully around the lengthwise axis.
The frame may include first and second end supports and at least one reinforcing element which extends between the first and second end supports so as to maintain the first and second end supports in a desired operative relationship.
In one form, the frame has a central lengthwise axis and further includes a second reinforcing element which extends between the first and second end supports. First and second lines extending from the central axis to the first and second reinforcing elements define an included angle of at least 90xc2x0. In one form, this included angle is 120xc2x0.
In one form, the frame has a central lengthwise axis and includes a second reinforcing element which extends between the first and second end supports, with the first and second end supports each including an elongate bar, with the first and second elongate bars being diametrically oppositely situated relative to the elongate central axis.
In one form, the external surface of the cage has a rounded shape. Alternatively, the external surface could have a squared shape, a cylindrical shape, or other shapes.